The long-term objective of this project is the introduction of a new system for out-of- hospital monitoring of cardiac patients. The system, called CardioAlarmTM, consists of a small sensor implanted under the skin and a "pocket receiver" that is carried by the patient in a pocket or purse, or kept within easy reach on a nearby desk, countertop, vanity, or nightstand. When the patient feels symptoms and pushes a button on the pocket receiver, the subcutaneous sensor transmits his/her electrocardiogram through the skin to the pocket receiver, which forwards it to a 24 hour cardiac monitoring service. In addition, if the sensor detects a dangerous heart rhythm and the patient becomes unconscious, the pocket receiver will sound an alarm that alerts nearby persons to call 911 for help. The CardioAlarm system addresses an unmet need for a monitor that can be used long-term by patients with a high risk of suffering cardiac arrest. In the US alone, nearly a quarter million people each year have a cardiac arrest and, because trained rescuers are not called or are called too late, only 2-5% of these survive. A system like CardioAlarm, which monitors the high-risk patient constantly, can significantly shorten the time to rescue and increase the chance of survival. It is estimated that the population with seriously elevated risk of cardiac arrest, but without indications for an implanted defibrillator, is over a million per year. In addition, because it is simple to implant, requires no cumbersome skin electrodes with associated cabling, and transmits each symptomatic event directly to a monitoring service, CardioAlarm will be well accepted by another, larger group of patients: those with unexplained syncope who require long-term monitoring to aid in the diagnosis of transient, infrequent symptoms. SBIR Phase I and II funding have resulted in the successful design, manufacture, and testing of the CardioAlarm system on the bench and in laboratory animals. This SBIR II Renewal application seeks further funding to complete FDA regulatory requirements necessary to introduce the system into the market. In its first year, the system will be tested to satisfy international standards for wireless telemetry, software reliability, and implant compatibility. In the second year the sensor will be implanted in select patients and the operation of the system will be verified during 12 months of follow up. PUBLIC HEALTH RELEVANCE In the US alone, nearly a quarter million people each year have a cardiac arrest and, because trained rescuers are not called or are called too late, only 2- 5% of these survive. The goal of this research is the introduction of a new system that will monitor heart patients, and sound an alarm to alert bystanders to call 911 if a dangerous heart rhythm occurs. This can significantly shorten the time to rescue and increase the chance of survival.